The present invention relates generally to an oil cooler for a larger-sized engine or the like, and particularly to an oil cooler configured to be mounted in a case in which cooling water flows.
Japanese Patent Application Publication (Translation of PCT Application) No. 2013-524157 (henceforth referred to as JP2013-524157) corresponding to United States Patent Application Publication 2013/025835 discloses an oil cooler including a plurality of flat tubes layered together with a clearance to one another in a layering direction, wherein the case allows cooling water to flow therein through the clearance in a longitudinal direction of the flat tubes, and wherein each flat tube allows working oil to flow therein. The oil cooler is employed in a state where the oil cooler is mounted in a case provided at a cylinder block or the like of a larger-sized engine. Cooling water of the engine is forced to circulate in the case, whereas working oil is sent under pressure to the oil cooler. The working oil is cooled by heat exchange with the cooling water. Japanese Patent Application Publication No. 2000-283661 (henceforth referred to as JP2000-283661) also discloses such an oil cooler.
The first plate and the second plate are formed of a clad material or the like, and joined to each other by brazing in a furnace in a state where a fin plate is sandwiched between the first and second plates.
Each plate of each flat tube 2 has an opening that serves as an oil inlet or oil outlet, wherein the periphery of the opening forms a cylindrical oil port, and the cylindrical oil port is connected to each other, to form a continuous oil inlet or outlet passage extending in the layering direction.
Heat exchange efficiency of such an oil cooler depends on flow rate and flow speed of cooling water flowing through the oil cooler. The oil cooler of JP2013-524157 is provided with an outer wall extending at a lateral periphery of the flat tube, and covering a lateral side of the flow passage of cooling water, to ensure flow of cooling water in the flow passage.